Multi-material fused deposition modeling (FDM) is an effective tool to realize the optimal design and manufacturing with various materials, but how to achieve an adequate level of interfacial bonding ...strength between dissimilar materials is still a critical problem. Herein, the influence of three multi-material FDM processing parameters, i.e. nozzle temperature, building stage temperature and printing speed, on the interfacial bonding strength of thermoplastic polyurethane (TPU)/acrylonitrile butadiene styrene (ABS) bi-material structures was experimentally investigated. It was found that the interfacial bonding strength was significantly improved from 0.86 to 1.66 MPa (increased by 93%) when the building stage temperature increased from 30 to 68 °C, which was the most effective processing parameter. Then, a heat transfer-based polymer inter-molecular diffusion theory was developed to understand the interfacial bonding mechanism. The interfacial temperature profiles during multi-material FDM process were experimentally measured by inserting thermocouples into printing specimens, and the theoretical model was well validated due to the good agreement between experimental and numerical data of interfacial temperature and bonding strength. The model provided an accurate prediction of interfacial bonding strength based on the understanding of thermally-driven diffusion of multi-material filaments; which would help improving the mechanical properties of products fabricated by multi-material FDM.
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•A heat transfer-based polymer inter-molecular diffusion theory is developed for multi-material FDM process•The interfacial temperature profiles during the multi-material FDM process are experimentally measured•The influence of processing parameters on interfacial bonding strength is investigated experimentally and numerically•The increase of building stage temperature significantly improves the interfacial bonding strength from 0.86 to 1.66 MPa•This study is helpful for design and optimization of the processing parameters of multi-material FDM
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Three-dimensional printing (3DP) is gaining momentum in the field of pharmaceuticals, offering innovative opportunities for medicine manufacture. Selective laser sintering (SLS) is a ...novel, high resolution and single-step printing technology that we have recently introduced to the pharmaceutical sciences. The aim of this work was to use SLS 3DP to fabricate printlets (3D printed tablets) with cylindrical, gyroid lattice and bi-layer structures having customisable release characteristics. Paracetamol-loaded constructs from four different pharmaceutical grade polymers including polyethylene oxide, Eudragit (L100-55 and RL) and ethyl cellulose, were created using SLS 3DP. The novel gyroid lattice structure was able to modulate the drug release from all four polymers. This work is the first to demonstrate the feasibility of using SLS to achieve customised drug release properties of several polymers, in a swift, cost-effective manner, avoiding the need to alter the formulation composition. By creating these constructs, it is therefore possible to modify drug release, which in practice, could enable the tailoring of drug performance to the patient simply by changing the 3D design.
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3D printing, and particularly fused deposition modeling (FDM), has rapidly brought the possibility of personalizing drug therapies to the forefront of pharmaceutical research and ...media attention. Applications for this technology, described in published articles, are expected to grow significantly in 2020. Where are we on this path, and what needs to be done to develop a FDM 2.0 process and make personalized medicines available to patients? Based on literature analysis, this manuscript aims to answer these questions and highlight the critical technical aspects of FDM as an emerging technology for manufacturing safe, high-quality personalized oral drug products. In this collaborative paper, experts from different fields contribute strategies for ensuring the quality of starting materials and discuss the design phase, printer hardware and software, the process, the environment and the resulting products, from the perspectives of both patients and operators.
Additive manufacturing of fiber reinforced composites is of great interest in various industrial applications. In this study, an innovative extruder is designed and manufactured for fused deposition ...modeling (FDM) 3D printers in order to produce continuous fiber reinforced thermoplastic (CFRT) composites. There are some challenges along this way such as making tension in fiber, fiber surface preparation, printing temperature and feed rate to produce a composite part with good quality. These challenges are discussed in detail. The main advantage of this extruder is that it can be mounted on the available FDM 3D printers and consequently there is no need to design a new chassis. In order to assess the quality of products, standard tensile and three-point bending specimens made of pure poly lactic acid (PLA) and carbon fiber reinforced PLA are printed and tested under quasi-static loading. Experimental results show significant improvements of tensile and bending properties of PLA. Morphological analysis is also conducted to study the bonding between the carbon fiber and PLA.
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Fused deposition modeling (FDM) printed polymers are rarely used as a structural material due to anisotropic and low mechanical properties compared with conventional composites. In recent years, ...greater need has been expressed for recycling of materials, such as recyclable FDM, at the end of service life to reduce environmental pollution and manufacture cost. However, how the amount of resin uptake in the skin and skin/core interphase affects the bending and shear performance of the sandwich composites when replacing the low strength and ductile core (conventional core) with a high strength and brittle core (FDM printed PLA (polylactic acid) core) still remains unclear. A new manufacturing routine is needed to improve the incorporation of FDM printed polymers in composite structures. In this work, FDM printed PLA was used as core material and sandwiched between two unidirectional glass fiber reinforced polymer (GFRP) skins to form a sandwich composite by compression-molding (CM) process, which provides a good manufacturing strategy for skin/core interphase modification. The significance of the CM process is proved by investigating the effect of resin uptake on bending and in-plane/out-of-plane shear performances. Current first order shear deformation (FSDT) theory lacks a direct connection between the in-plane shear stress and out-of-shear stress in the core region of sandwich composites. With the help of DIC, a connection between the in-plane shear and the out-of-plane shear strain was built and in-plane shear properties can acquire through out-of-plane shear properties, hence reducing the redundancy of sample preparation or the need for simulation. A significant improvement was found compared with the optimized resin uptake (Optimized resin uptake range: 20.43%–22.86 wt%) 3D-printed PLA core sandwich composite and lowest performance sandwich composite (Improvement: in-plane shear strength (∼34%)/modulus (∼29%), out-of-plane shear strength (∼25%)/modulus (∼31%), specific peak bending load (∼19%)). Compared with balsa core sandwich composites, the 3D-printed cores are suitable for use in composite sandwich structures in many applications with a satisfactory strength-to-weight ratio.
This paper reports the thermal and mechanical properties of carbon fiber (CF) reinforced polyamide 12 (PA12) composites for fused deposition modeling (FDM) process. The printable filaments of carbon ...fiber/PA12 composites with different mass fraction were fabricated and applied in FDM. The results indicate that the tensile strength and flexural strength of 10 wt% CF/PA12 composites are enhanced by 102.2% and 251.1% respectively. The laser-flash diffusivity analysis measurements exhibit remarkable improvements on thermal conductivity (λ) of carbon fiber/PA12 composites. Moreover, the carbon fiber/PA12 composites mechanical properties are greatly improved. Our work presents a kind of anisotropic high performance composite for FDM.
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•Filament which can be smoothly printed via a FDM printer was prepared by melt compounding.•Carbon fibers are dispersed uniformly and preferentially aligned along the printing direction.•Tensile and flexure properties were improved significantly without sacrificing the impact properties.•The thermal conductivity was improved significantly.
Fused deposition modeling (FDM) is one of the most popular additive manufacturing technologies for various engineering applications. FDM process has been introduced commercially in early 1990s by ...Stratasys Inc., USA. The quality of FDM processed parts mainly depends on careful selection of process variables. Thus, identification of the FDM process parameters that significantly affect the quality of FDM processed parts is important. In recent years, researchers have explored a number of ways to improve the mechanical properties and part quality using various experimental design techniques and concepts. This article aims to review the research carried out so far in determining and optimizing the process parameters of the FDM process. Several statistical designs of experiments and optimization techniques used for the determination of optimum process parameters have been examined. The trends for future FDM research in this area are described.
•Under dominantly pure mode I loading conditions, the crack growth path of the AM SCBs under dynamic conditions was very similar to the homogenous specimens.•The average dynamic fracture energies in ...pure mode I and pure mode II were about 731% and 136% higher than the static state, respectively for the presented FDM samples.•A finite element model based on the EMC-GMTS failure theory can successfully predict the failure manner of the presented 3D-printed cracked components.
In the practical implementation of the Additively Manufactured (AM) construction in engineering designs, Fused Deposition Modeling (FDM) is recently used to manufacture the inexpensive Acrylonitrile Butadiene Styrene (ABS) parts. The cracking behaviors of such layered components are inspected using the Semi-Circular Bending (SCB) fracture samples. In particular, the effect of anisotropy or layered nature of 3D printed specimens is only considered on the fracture manner among the affecting parameters. The dynamic and static three-point bend tests are conducted from pure mode I to pure mode II conditions. Dynamic experiments are performed using a modified Charpy instrument, and the required energies for the crack initiation are obtained. In the next step, a finite element model based on the Equivalent Material Concept-Generalized Maximum Tangential Stress (EMC-GMTS) failure theory is introduced, and its predictions are compared with the obtained experimental data. Under different loading rates, the crack path trajectories and fracture behavior is surveyed in detail concerning the isotropic counterparts in two micro and macro scales. According to the SEM images and the validity of the brittle fracture theory (with a maximum of 5% error), it is proved that the SCB samples made from ABS are fractured in a brittle manner. The fracture behavior of the FDM 3D-printed structures under dynamic loading conditions is analogous to those homogenous materials, especially where the mode I deformation is dominant. Also, the dynamic and static paths for dominantly pure mode II loading conditions are nearly identical.
Fused deposition modeling (FDM) is one of the most commonly utilized low-cost 3D printing technology, which employs the hot-melt and adhesive properties of thermoplastic materials. As one of the most ...important classes of engineering thermoplastic polymer materials, polyamide (PA) possesses excellent comprehensive performance. However, the FDM fabricated products based on pure PA are seriously warped, distorted, and lack of shape stability due to the accumulation of shrinkage stress generated from the crystallization of polymer, which severely restrict the application of PA in FDM 3D printing. In this article, notable advances in FDM 3D printing of polyamide-based composites and the properties of the printed parts as well as their practical or potential applications are highlighted. The particular emphasis is placed on the formation and the performance of polyamide/polymer blends, inorganic particle reinforced polyamide composites, and fiber reinforced polyamide composites. Finally, the significant limitations, opportunities, and challenges are identified to motivate the future research on the FDM 3D printing of polyamide-based composites and its applications.
•A brief review of notable advances in fused deposition modeling (FDM) 3D printing of polyamide-based composites and the properties of the printed parts as well as their practical or potential applications is presented.•The formation and the performance of polyamide/polymer blends, inorganic particle reinforced polyamide composites, and fiber reinforced polyamide composites have been particularly emphasized.•The significant limitations, opportunities, and challenges are identified to motivate the future research on FDM 3D printing of polyamide-based composites and its applications.
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